1 6848 133 [MOLECULAR GENETIC AND EPIGENETIC MECHANISMS OF HEPATOCARCINOGENESIS]. HEPATOCELLULAR CARCINOMA (HCC) IS A MAJOR TYPE OF PRIMARY LIVER CANCER AND ONE OF THE MOST FREQUENT HUMAN MALIGNANT NEOPLASMS. COMMON RISK FACTORS OF HUMAN HCC INCLUDE CHRONIC HEPATITIS VIRUS (HBV AND HCV) INFECTION, DIETARY AFLATOXIN B1 (AFB1) INGESTION, CHRONIC ALCOHOL ABUSE, AND CIRRHOSIS ASSOCIATED WITH GENETIC LIVER DISEASES. HEPATOCARCINOGENESIS IS THE RESULT OF INTERACTION BETWEEN HEREDITARY AND ENVIRONMENTAL FACTORS. INHERITANCE DETERMINES INDIVIDUAL SUSCEPTIBILITY TO CANCER; ENVIRONMENT DETERMINES WHICH SUSCEPTIBLE INDIVIDUALS EXPRESS CANCER. STUDIES OF GENETIC AND EPIGENETIC MECHANISMS OF HEPATOCARCINOGENESIS SHOWED THAT HCC DEVELOPMENT IS A COMPLEX POLYGENE AND MULTIPATHWAY PROCESS; THE ACTIVATION OF PROTO-ONCOGENES AND THE INACTIVATION OF TUMOR SUPPRESSOR GENES INDUCED BY GENETIC AND EPIGENETIC ALTERATIONS ARE CORE BIOLOGICAL PROCESSES OF HEPATOCARCINOGENESIS; RB1, P53, AND WNT PATHWAYS ARE COMMONLY AFFECTED IN HCCS OF DIFFERENT ETIOLOGIES, WHICH MAY REFLECT COMMON PATHOLOGIC SEQUENCE OF HCC: CHRONIC LIVER INJURY, CIRRHOSIS, ATYPICAL HYPERPLASTIC NODULES, AND HCC OF EARLY STAGES. HEPATITIS VIRUS INFECTION-ASSOCIATED HCCS HAVE FREQUENT ALTERATIONS IN RB1 PATHWAY, INCLUDING METHYLATION OF P16INK4A AND RB1 GENES AND AMPLIFICATION OF CYCLIN D1. AFB1 EXPOSURE-ASSOCIATED HCCS HAVE FREQUENT ALTERATIONS IN P53 PATHWAY; THE G-->T MUTATION OF P53 GENE AT CODON 249 HAS BEEN IDENTIFIED AS A GENETIC HALLMARK OF HCC CAUSED BY AFB1. ALCOHOLISM-ASSOCIATED HCCS HAVE FREQUENT ALTERATIONS IN BOTH RB1 AND P53 PATHWAYS. THE ROLES OF SOME IMPORTANT GENES RELATED TO CELL APOPTOSIS, DNA REPAIR, DRUG METABOLISM, AND TUMOR METASTASIS IN HEPATOCARCINOGENESIS HAD BEEN DISCUSSED. 2005 2 3567 40 IMPACT OF HEPATITIS VIRUS AND AGING ON DNA METHYLATION IN HUMAN HEPATOCARCINOGENESIS. HEPATOCELLULAR CARCINOMA (HCC) USUALLY DEVELOPS ON THE BASIS OF CHRONIC HEPATITIS AND LIVER CIRRHOSIS, WHERE INACTIVATION OF SEVERAL TUMOR SUPPRESSOR GENES (TSGS) TAKES PLACE VIA METHYLATION OF THE PROMOTER. INTERESTINGLY, THESE METHYLATION EVENTS ARE MORE PREVALENT IN A BACKGROUND LIVER AT HIGH RISK OF HCC THAN ONE AT LOW RISK. ABNORMAL METHYLATION IS ALSO OBSERVED IN PRECANCEROUS NODULES SUCH AS DYSPLASTIC NODULES AND ADENOMAS, SUGGESTING THAT EPIGENETIC ALTERATION IS AN EARLY EVENT FOR HCC CARCINOGENESIS. IT IS POSSIBLE THAT INFECTION WITH THE HEPATITIS VIRUS INDUCES ALTERATION OF METHYLATION AT PROMOTERS OF TSGS. SOME STUDIES SUGGESTED THAT VIRAL PROTEINS INTERFERE WITH DNA METHYLTRANSFERASE IN CHRONIC HEPATITIS B. INDUCTION OF EPIGENETIC ALTERATION IN CHRONIC HEPATITIS C MIGHT, HOWEVER, MIGHT BE A CONSEQUENCE OF OXIDATIVE STRESS. IN ADDITION, WE PROPOSED AGE SHOULD BE TAKEN INTO CONSIDERATION FOR HCC DEVELOPMENT VIA EPIGENETIC PATHWAYS. FURTHER INVESTIGATIONS ARE REQUIRED TO UNDERSTAND THE MECHANISM OF INDUCING EPIGENETIC INSTABILITY DURING HEPATOCARCINOGENESIS. 2010 3 4134 62 MECHANISMS OF HUMAN HEPATOCARCINOGENESIS. THE MAJOR RISK FACTORS AND ETIOLOGICAL AGENTS RESPONSIBLE FOR DEVELOPMENT OF HEPATOCELLULAR CARCINOMA IN HUMANS HAVE BEEN IDENTIFIED AND CHARACTERIZED. AMONG THESE ARE CHRONIC INFECTION WITH HEPATITIS B VIRUS OR HEPATITIS C VIRUS, EXPOSURE TO AFLATOXIN B1, AND CIRRHOSIS OF ANY ETIOLOGY (INCLUDING ALCOHOLIC CIRRHOSIS AND CIRRHOSIS ASSOCIATED WITH GENETIC LIVER DISEASES). BOTH CHRONIC HEPATITIS AND CIRRHOSIS REPRESENT MAJOR PRENEOPLASTIC CONDITIONS OF THE LIVER AS THE MAJORITY OF HEPATOCELLULAR CARCINOMAS ARISE IN THESE PATHOLOGICAL SETTINGS. HEPATOCARCINOGENESIS REPRESENTS A LINEAR AND PROGRESSIVE PROCESS IN WHICH SUCCESSIVELY MORE ABERRANT MONOCLONAL POPULATIONS OF HEPATOCYTES EVOLVE. REGENERATIVE HEPATOCYTES IN FOCAL LESIONS IN THE INFLAMED LIVER (CHRONIC HEPATITIS OR CIRRHOSIS) GIVE RISE TO HYPERPLASTIC HEPATOCYTE NODULES, AND THESE PROGRESS TO DYSPLASTIC NODULES, WHICH ARE THOUGHT TO BE THE DIRECT PRECURSOR OF HEPATOCELLULAR CARCINOMA. IN MOST CASES, THE NEOPLASTIC TRANSFORMATION OF HEPATOCYTES RESULTS FROM ACCUMULATION OF GENETIC DAMAGE DURING THE REPETITIVE CELLULAR PROLIFERATION THAT OCCURS IN THE INJURED LIVER IN RESPONSE TO PARACRINE GROWTH FACTOR AND CYTOKINE STIMULATION. HEPATOCELLULAR CARCINOMAS EXHIBIT NUMEROUS GENETIC ABNORMALITIES (INCLUDING CHROMOSOMAL DELETIONS, REARRANGEMENTS, ANEUPLOIDY, GENE AMPLIFICATIONS, AND MUTATIONS), AS WELL AS EPIGENETIC ALTERATIONS (INCLUDING MODULATION OF DNA METHYLATION). THESE GENETIC AND EPIGENETIC ALTERATIONS COMBINE TO ACTIVATE POSITIVE MEDIATORS OF CELLULAR PROLIFERATION (INCLUDING CELLULAR PROTO-ONCOGENES AND THEIR MITOGENIC SIGNALING PATHWAYS) AND INACTIVATE NEGATIVE MEDIATORS OF CELLULAR PROLIFERATION (INCLUDING TUMOR SUPPRESSOR GENES), RESULTING IN CELLS WITH AUTONOMOUS GROWTH POTENTIAL. HOWEVER, HEPATOCELLULAR CARCINOMAS EXHIBIT A HIGH DEGREE OF GENETIC HETEROGENEITY, SUGGESTING THAT MULTIPLE MOLECULAR PATHWAYS MAY BE INVOLVED IN THE GENESIS OF SUBSETS OF HEPATOCELLULAR NEOPLASMS. CONTINUED INVESTIGATION OF THE MECHANISMS OF HEPATOCARCINOGENESIS WILL REFINE OUR CURRENT UNDERSTANDING OF THE MOLECULAR AND CELLULAR BASIS FOR NEOPLASTIC TRANSFORMATION IN LIVER, ENABLING THE DEVELOPMENT OF EFFECTIVE STRATEGIES FOR PREVENTION AND/OR MORE EFFECTIVE TREATMENT OF HEPATOCELLULAR CARCINOMA. 2003 4 5360 45 RECENT ADVANCEMENTS IN COMPREHENSIVE GENETIC ANALYSES FOR HUMAN HEPATOCELLULAR CARCINOMA. HEPATOCELLULAR CARCINOMA (HCC) TYPICALLY DEVELOPS IN THE LIVER WITH CHRONIC HEPATITIS AND CIRRHOSIS, AND ACTIVATION OF ONCOGENES AND INACTIVATION OF TUMOR SUPPRESSOR GENES OCCURS DURING CARCINOGENESIS VIA GENETIC AND EPIGENETIC MECHANISMS. RECENT ADVANCEMENTS IN THE DEVELOPMENT OF ANALYSES FOR EXAMINING THE CANCER GENOME HAVE REVEALED INFORMATION REGARDING GENETIC ALTERATIONS IN HCC TISSUES. ACCORDING TO PREVIOUS STUDIES, THE INCIDENCE OF RECURRENT GENETIC ALTERATIONS IN INDIVIDUAL GENES WAS THOUGHT TO BE RELATIVELY RARE AND LIMITED TO A SUBSET OF A FEW CANCER-SPECIFIC GENES SUCH AS TUMOR SUPPRESSOR P53, RB GENES AND ONCOGENES SUCH AS CTNNB1. HOWEVER, RECENT WHOLE-GENOME ANALYSES AND EXOME SEQUENCING OF TUMOR DNA HAVE REVEALED NUMEROUS NOVEL ALTERATIONS OF CANCER-RELATED GENES AND PATHWAYS CRITICAL FOR HCC DEVELOPMENT. IN ADDITION, VARIOUS RISK FACTORS FOR HCC, SUCH AS THE PRESENCE OR ABSENCE OF HEPATITIS B AND C VIRUS, MAY AFFECT THE MUTATION PROFILE OF THE CORRESPONDING CANCER GENOME. ON THE OTHER HAND, GENOME-WIDE ASSOCIATION STUDIES HAVE ALSO IDENTIFIED IMPORTANT SINGLE-NUCLEOTIDE POLYMORPHISMS INVOLVED IN HCC DEVELOPMENT, WHICH MAY ALLOW DETECTION OF A GROUP AT HIGH RISK OF HCC EMERGENCE. SUCH ANALYSES WILL CLARIFY HOW THIS MALIGNANCY CAN BE TREATED, DIAGNOSED AND PREVENTED MORE EFFECTIVELY. 2013 5 1543 32 DNA METHYLATION IN HEPATOCELLULAR CARCINOMA. AS FOR MANY OTHER TUMORS, DEVELOPMENT OF HEPATOCELLULAR CARCINOMA (HCC) MUST BE UNDERSTOOD AS A MULTISTEP PROCESS WITH ACCUMULATION OF GENETIC AND EPIGENETIC ALTERATIONS IN REGULATORY GENES, LEADING TO ACTIVATION OF ONCOGENES AND INACTIVATION OR LOSS OF TUMOR SUPPRESSOR GENES (TSG). IN THE LAST DECADES, IN ADDITION TO GENETIC ALTERATIONS, EPIGENETIC INACTIVATION OF (TUMOR SUPPRESSOR) GENES BY PROMOTER HYPERMETHYLATION HAS BEEN RECOGNIZED AS AN IMPORTANT AND ALTERNATIVE MECHANISM IN TUMORIGENESIS. IN HCC, ABERRANT METHYLATION OF PROMOTER SEQUENCES OCCURS NOT ONLY IN ADVANCED TUMORS, IT HAS BEEN ALSO OBSERVED IN PREMALIGNANT CONDITIONS JUST AS CHRONIC VIRAL HEPATITIS B OR C AND CIRRHOTIC LIVER. THIS REVIEW DISCUSSES THE EPIGENETIC ALTERATIONS IN HEPATOCELLULAR CARCINOMA FOCUSING DNA METHYLATION. 2008 6 4920 38 PARALLEL EPIGENETIC AND GENETIC CHANGES IN THE PATHOGENESIS OF HEPATITIS VIRUS-ASSOCIATED HEPATOCELLULAR CARCINOMA. HEPATOCELLULAR CARCINOMA (HCC) IS ONE OF THE MOST FREQUENT TUMOR TYPES IN THE WORLD, WITH SHORT SURVIVAL TIMES AND FEW TREATMENT OPTIONS. HEPATITIS B VIRUS (HBV) AND HEPATITIS C VIRUS (HCV) ARE MAJOR ETIOLOGIC AGENTS OF HCC, ALTHOUGH THE ASSOCIATED MECHANISMS ARE INCOMPLETELY UNDERSTOOD. THE AVAILABLE EVIDENCE SUGGESTS THAT BOTH VIRUSES PROMOTE TUMORIGENESIS BY UP-REGULATING GENES THAT PROMOTE HEPATOCELLULAR GROWTH AND SURVIVAL, AND BY DOWN-REGULATING OTHER GENES THAT ACT AS TUMOR SUPPRESSORS AND NEGATIVE GROWTH REGULATORY MOLECULES. SIGNIFICANTLY, A NUMBER OF THE PATHWAYS THAT ARE ALTERED BY THESE VIRUSES ARE THE SAME ONES THAT ACCUMULATE GENETIC ALTERATIONS DURING TUMOR PROGRESSION. THIS SUGGESTS THAT THE PATHWAYS THAT PROMOTE VIRUS PERSISTENCE AND REPLICATION MAY ALSO PROMOTE CELL GROWTH AND SURVIVAL. FROM THE PERSPECTIVE OF THE VIRUS, THIS PROMOTES CHRONIC INFECTION, WHILE FROM THE PERSPECTIVE OF THE HOST, THIS PROMOTES TUMORIGENESIS. 2006 7 6487 58 TP53 MUTATIONS AND HEPATOCELLULAR CARCINOMA: INSIGHTS INTO THE ETIOLOGY AND PATHOGENESIS OF LIVER CANCER. HEPATOCELLULAR CARCINOMA (HCC) IS ONE OF THE MOST COMMON MALIGNANCIES WORLDWIDE AND THE MAJOR RISK FACTORS INCLUDE CHRONIC INFECTIONS WITH THE HEPATITIS B (HBV) OR C (HCV) VIRUS, AND EXPOSURE TO DIETARY AFLATOXIN B(1) (AFB(1)) OR ALCOHOL CONSUMPTION. MULTIPLE GENETIC AND EPIGENETIC CHANGES ARE INVOLVED IN THE MOLECULAR PATHOGENESIS OF HCC, FOR EXAMPLE, SOMATIC MUTATIONS IN THE P53 TUMOR SUPPRESSOR GENE (TP53) AND THE ACTIVATION OF THE WNT SIGNAL TRANSDUCTION PATHWAY. AFB(1) FREQUENTLY INDUCES G:C TO T:A TRANSVERSIONS AT THE THIRD BASE IN CODON 249 OF TP53 AND COOPERATES WITH HBV IN CAUSING P53 MUTATIONS IN HCC. THE DETECTION OF TP53 MUTANT DNA IN PLASMA IS A BIOMARKER OF BOTH AFB(1) EXPOSURE AND HCC RISK. CHRONIC INFECTION WITH HBV AND HCV VIRUSES, AND OXYRADICAL DISORDERS INCLUDING HEMOCHROMATOSIS, ALSO GENERATE REACTIVE OXYGEN/NITROGEN SPECIES THAT CAN BOTH DAMAGE DNA AND MUTATE CANCER-RELATED GENES SUCH AS TP53. CERTAIN MUTANT P53 PROTEINS MAY EXHIBIT A 'GAIN OF ONCOGENIC FUNCTION'. THE P53 BIOLOGICAL NETWORK IS A KEY RESPONDER TO THIS OXIDATIVE AND NITROSATIVE STRESS. DEPENDING ON THE EXTENT OF THE DNA DAMAGE, P53 REGULATES THE TRANSCRIPTION OF PROTECTIVE ANTIOXIDANT GENES AND WITH EXTENSIVE DNA DAMAGE, TRANSACTIVATES PRO-OXIDANT GENES THAT CONTRIBUTE TO APOPTOSIS. THE X GENE OF HBV (HBX) IS THE MOST COMMON OPEN READING FRAME INTEGRATED INTO THE HOST GENOME IN HCC AND THE INTEGRATED HBX IS FREQUENTLY MUTATED. MUTANT HBX PROTEINS STILL RETAIN THEIR ABILITY TO BIND TO P53, AND ATTENUATE DNA REPAIR AND P53-MEDIATED APOPTOSIS. IN SUMMARY, BOTH VIRUSES AND CHEMICALS ARE IMPLICATED IN THE ETIOLOGY OF TP53 MUTATIONS DURING THE MOLECULAR PATHOGENESIS OF HCC. 2007 8 6797 39 [EPIDEMIOLOGY, NATURAL HISTORY AND PATHOGENESIS OF HEPATOCELLULAR CARCINOMA]. HEPATOCELLULAR CARCINOMA (HCC) IS THE MAIN TYPE OF PRIMARY LIVER CANCERS AND THE THIRD MOST COMMON CAUSE OF CANCER MORTALITY WORLDWIDE. IN FRANCE, RISING NUMBER BETWEEN 5000 AND 6000 CASES ARE DIAGNOSED EACH YEAR. THE MAJOR RISK FACTOR FOR HEPATOCELLULAR CARCINOMA IS CHRONIC HEPATITIS: VIRAL HEPATITIS B, VIRAL HEPATITIS C, CONSUMPTION OF ALCOHOL, HEMOCHROMATOSIS. HEPATOCELLULAR CARCINOMA IS CLOSELY ASSOCIATED TO LIVER CIRRHOSIS, WHICH IS A TRUE PRECANCEROUS STATE. BECAUSE HEPATOCARCINOGENESIS IS A LONG AND HETEROGENEOUS PROCESS, THERE IS STILL MUCH TO UNDERSTAND. MANY GENETIC AND EPIGENETIC ALTERATIONS ARE DESCRIBED LEADING TO CHANGES IN CELLULAR SIGNALLING CASCADES INVOLVED IN REGULATION OF GROWTH, DIFFERENTIATION, APOPTOSIS, MOTILITY. HEPATITIS VIRUSES PLAY A DIRECT ONCOGENIC ROLE THROUGH THE INTERACTION BETWEEN VIRAL AND CELLULAR PROTEINS, WHICH CONTROL CELL HOMEOSTASIS, OR BY THE INTEGRATION OF HEPATITIS B VIRUS GENOME INTO THE HOST GENOME. FURTHERMORE, HEPATITIS VIRUSES PLAY AN INDIRECT ONCOGENIC ROLE BY CAUSING CHRONIC INFLAMMATION AND HEPATOCYTE REGENERATION RELATED TO VIRAL HEPATOPATHY. IN EXPECTATION OF A BETTER UNDERSTANDING OF HEPATOCARCINOGENESIS AND NEW TREATMENTS, PREVENTION FROM RISK FACTORS AND ULTRASONOGRAPHIC SCREENING OF PATIENTS WITH CIRRHOSIS SHOULD INCREASE PROGNOSIS. 2011 9 4476 33 MOLECULAR PATHOGENESIS OF HEPATOCELLULAR CARCINOMA. HEPATOCELLULAR CARCINOMA (HCC) IS THE FIFTH MOST COMMON CANCER AND THE THIRD LEADING CAUSE OF CANCER DEATH WORLDWIDE. HEPATOCARCINOGENESIS IS A MULTISTEP PROCESS EVOLVING FROM NORMAL THROUGH CHRONIC HEPATITIS/CIRRHOSIS AND DYSPLASTIC NODULES TO HCC. WITH ADVANCES IN MOLECULAR METHODS, THERE IS A GROWING UNDERSTANDING OF THE MOLECULAR MECHANISMS IN HEPATOCARCINOGENESIS. HEPATOCARCINOGENESIS IS STRONGLY LINKED TO INCREASES IN ALLELIC LOSSES, CHROMOSOMAL CHANGES, GENE MUTATIONS, EPIGENETIC ALTERATIONS AND ALTERATIONS IN MOLECULAR CELLULAR PATHWAYS. SOME OF THESE ALTERATIONS ARE ACCOMPANIED BY A STEPWISE INCREASE IN THE DIFFERENT PATHOLOGICAL DISEASE STAGES IN HEPATOCARCINOGENESIS. OVERALL, A DETAILED UNDERSTANDING OF THE UNDERLYING MOLECULAR MECHANISMS INVOLVED IN THE PROGRESSION OF HCC IS OF FUNDAMENTAL IMPORTANCE TO THE DEVELOPMENT OF EFFECTIVE PREVENTION AND TREATMENT REGIMES FOR HCC. 2008 10 2172 38 EPIGENETIC MECHANISMS INVOLVED IN HCV-INDUCED HEPATOCELLULAR CARCINOMA (HCC). HEPATOCELLULAR CARCINOMA (HCC), IS THE THIRD LEADING CAUSE OF CANCER-RELATED DEATHS, WHICH IS LARGELY CAUSED BY VIRUS INFECTION. ABOUT 80% OF THE VIRUS-INFECTED PEOPLE DEVELOP A CHRONIC INFECTION THAT EVENTUALLY LEADS TO LIVER CIRRHOSIS AND HEPATOCELLULAR CARCINOMA (HCC). WITH APPROXIMATELY 71 MILLION HCV CHRONIC INFECTED PATIENTS WORLDWIDE, THEY STILL HAVE A HIGH RISK OF HCC IN THE NEAR FUTURE. HOWEVER, THE MECHANISMS OF CARCINOGENESIS IN CHRONIC HCV INFECTION HAVE NOT BEEN STILL FULLY UNDERSTOOD, WHICH INVOLVE A COMPLEX EPIGENETIC REGULATION AND CELLULAR SIGNALING PATHWAYS. HERE, WE SUMMARIZE 18 SPECIFIC GENE TARGETS AND DIFFERENT SIGNALING PATHWAYS INVOLVED IN RECENT FINDINGS. WITH THESE EPIGENETIC ALTERATIONS REQUIRING HISTONE MODIFICATIONS AND DNA HYPER OR HYPO-METHYLATION OF THESE SPECIFIC GENES, THE DYSREGULATION OF GENE EXPRESSION IS ALSO ASSOCIATED WITH DIFFERENT SIGNALING PATHWAYS FOR THE HCV LIFE CYCLE AND HCC. THESE FINDINGS PROVIDE A NOVEL INSIGHT INTO A CORRELATION BETWEEN HCV INFECTION AND HCC TUMORIGENESIS, AS WELL AS POTENTIALLY PREVENTABLE APPROACHES. HEPATITIS C VIRUS (HCV) INFECTION LARGELY CAUSES HEPATOCELLULAR CARCINOMA (HCC) WORLDWIDE WITH 3 TO 4 MILLION NEWLY INFECTED CASES DIAGNOSED EACH YEAR. IT IS URGENT TO EXPLORE ITS UNDERLYING MOLECULAR MECHANISMS FOR THERAPEUTIC TREATMENT AND BIOMARKER DISCOVERY. HOWEVER, THE MECHANISMS OF CARCINOGENESIS IN CHRONIC HCV INFECTION HAVE NOT BEEN STILL FULLY UNDERSTOOD, WHICH INVOLVE A COMPLEX EPIGENETIC REGULATION AND CELLULAR SIGNALING PATHWAYS. HERE, WE SUMMARIZE 18 SPECIFIC GENE TARGETS AND DIFFERENT SIGNALING PATHWAYS INVOLVED IN RECENT FINDINGS. WITH THESE EPIGENETIC ALTERATIONS REQUIRING HISTONE MODIFICATIONS AND DNA HYPER OR HYPO-METHYLATION OF THESE SPECIFIC GENES, THE DYSREGULATION OF GENE EXPRESSION IS ALSO ASSOCIATED WITH DIFFERENT SIGNALING PATHWAYS FOR THE HCV LIFE CYCLE AND HCC. THESE FINDINGS PROVIDE A NOVEL INSIGHT INTO A CORRELATION BETWEEN HCV INFECTION AND HCC TUMORIGENESIS, AS WELL AS POTENTIALLY PREVENTABLE APPROACHES. 2021 11 6798 42 [EPIDEMIOLOGY, RISK FACTORS AND MOLECULAR PATHOGENESIS OF PRIMARY LIVER CANCER]. PRIMARY LIVER CANCER IS THE FIFTH MOST COMMON CANCER WORLDWIDE. HEPATOCELLULAR CARCINOMA ACCOUNTS FOR 85-90% OF PRIMARY LIVER CANCERS. DISTRIBUTION OF HEPATOCELLULAR CARCINOMA SHOWS VARIATIONS AMONG GEOGRAPHIC REGIONS AND ETHNIC GROUPS. MALES HAVE HIGHER LIVER CANCER RATES THAN FEMALES. HEPATOCELLULAR CARCINOMA OCCURS WITHIN AN ESTABLISHED BACKGROUND OF CHRONIC LIVER DISEASE AND CIRRHOSIS (70-90%). MAJOR CAUSES (80%) OF HEPATOCELLULAR CARCINOMA ARE HEPATITIS B, C VIRUS INFECTION, AND AFLATOXIN EXPOSITION. ITS DEVELOPMENT IS A MULTISTEP PROCESS. WE HAVE A GROWING UNDERSTANDING ON THE MOLECULAR PATHOGENESIS. GENETIC AND EPIGENETIC CHANGES ACTIVATE ONCOGENES, INHIBIT TUMORSUPPRESSOR GENES, WHICH RESULT IN AUTONOMOUS CELL PROLIFERATION. THE CHROMOSOMAL INSTABILITY CAUSED BY TELOMERE DYSFUNCTION, THE GROWTH-RETRAINED ENVIRONMENT AND THE ALTERATIONS OF THE MICRO- AND MACROENVIRONMENT HELP THE EXPANSION OF THE MALIGNANT CELLS. UNDERSTANDING THE MOLECULAR MECHANISMS COULD IMPROVE THE SCREENING OF PATIENTS WITH CHRONIC LIVER DISEASE, OR CIRRHOSIS, AND THE PREVENTION AS WELL AS TREATMENT OF HEPATOCELLULAR CARCINOMA. 2008 12 4461 37 MOLECULAR MECHANISMS OF GENDER DISPARITY IN HEPATITIS B VIRUS-ASSOCIATED HEPATOCELLULAR CARCINOMA. CHRONIC HEPATITIS B VIRUS (HBV) INFECTION IS ONE OF THE MOST COMMON CAUSES OF HEPATOCELLULAR CARCINOMA (HCC), A MALIGNANT TUMOR WITH HIGH MORTALITY WORLDWIDE. ONE REMARKABLE CLINICAL FEATURE OF HBV-RELATED HCC IS THAT ITS INCIDENCE IS HIGHER IN MALES AND POSTMENOPAUSAL FEMALES COMPARED TO OTHER FEMALES. INCREASING EVIDENCE INDICATES THAT HBV-ASSOCIATED HCC MAY INVOLVE GENDER DISPARITY AND THAT IT MAY BE A TYPE OF HORMONE-RESPONSIVE MALIGNANT TUMOR. SEX HORMONES, SUCH AS ANDROGEN AND ESTROGEN, HAVE BEEN SHOWN TO PLAY VERY DIFFERENT ROLES IN THE PROGRESSION OF AN HBV INFECTION AND IN THE DEVELOPMENT OF HBV-RELATED HCC. THROUGH BINDING TO THEIR SPECIFIC CELLULAR RECEPTORS AND AFFECTING THE CORRESPONDING SIGNALING PATHWAYS, SEX HORMONES CAN REGULATE THE TRANSACTIVATION OF HBX, CAUSE THE CHRONIC RELEASE OF INFLAMMATORY CYTOKINES IN THE HEPATOCELLULAR MICROENVIRONMENT, AND PARTICIPATE IN EPIGENETIC AND GENETIC ALTERNATIONS IN HEPATOCYTES. ALL OF THESE FUNCTIONS MAY BE RELATED TO THE INITIATION AND PROGRESSION OF HBV-ASSOCIATED HCC. A THOROUGH INVESTIGATION OF THE MOLECULAR MECHANISMS UNDERLYING THE GENDER-RELATED DISPARITY IN HBV-RELATED HCC SHOULD PROVIDE A NEW PERSPECTIVE FOR BETTER UNDERSTANDING ITS PATHOGENESIS AND EXPLORING MORE EFFECTIVE METHODS FOR THE PREVENTION AND TREATMENT OF THIS DISEASE. 2014 13 4477 34 MOLECULAR PATHOGENESIS OF HUMAN HEPATOCELLULAR CARCINOMA. HEPATOCARCINOGENESIS IS A SLOW PROCESS DURING WHICH GENOMIC CHANGES PROGRESSIVELY ALTER THE HEPATOCELLULAR PHENOTYPE TO PRODUCE CELLULAR INTERMEDIATES THAT EVOLVE INTO HEPATOCELLULAR CARCINOMA. DURING THE LONG PRENEOPLASTIC STAGE, IN WHICH THE LIVER IS OFTEN THE SITE OF CHRONIC HEPATITIS, CIRRHOSIS, OR BOTH, HEPATOCYTE CYCLING IS ACCELERATED BY UPREGULATION OF MITOGENIC PATHWAYS, IN PART THROUGH EPIGENETIC MECHANISMS. THIS LEADS TO THE PRODUCTION OF MONOCLONAL POPULATIONS OF ABERRANT AND DYSPLASTIC HEPATOCYTES THAT HAVE TELOMERE EROSION AND TELOMERASE RE-EXPRESSION, SOMETIMES MICROSATELLITE INSTABILITY, AND OCCASIONALLY STRUCTURAL ABERRATIONS IN GENES AND CHROMOSOMES. DEVELOPMENT OF DYSPLASTIC HEPATOCYTES IN FOCI AND NODULES AND EMERGENCE OF HEPATOCELLULAR CARCINOMA ARE ASSOCIATED WITH THE ACCUMULATION OF IRREVERSIBLE STRUCTURAL ALTERATIONS IN GENES AND CHROMOSOMES, BUT THE GENOMIC BASIS OF THE MALIGNANT PHENOTYPE IS HETEROGENEOUS. THE MALIGNANT HEPATOCYTE PHENOTYPE MAY BE PRODUCED BY THE DISRUPTION OF A NUMBER OF GENES THAT FUNCTION IN DIFFERENT REGULATORY PATHWAYS, PRODUCING SEVERAL MOLECULAR VARIANTS OF HEPATOCELLULAR CARCINOMA. NEW STRATEGIES SHOULD ENABLE THESE VARIANTS TO BE CHARACTERIZED. 2002 14 332 43 ALTERATION OF EPIGENETIC PROFILE IN HUMAN HEPATOCELLULAR CARCINOMA AND ITS CLINICAL IMPLICATIONS. HEPATOCELLULAR CARCINOMA (HCC) IS A COMMON CANCER WORLDWIDE AND DEVELOPS AGAINST A BACKGROUND OF CHRONIC LIVER DAMAGE. A VARIETY OF HCC-RELATED GENES ARE KNOWN TO BE ALTERED BY GENETIC AND EPIGENETIC MECHANISMS. THEREFORE, INFORMATION REGARDING ALTERATION OF THE GENETIC AND EPIGENETIC PROFILES IN HCC IS ESSENTIAL FOR UNDERSTANDING THE BIOLOGY OF THIS TYPE OF TUMOR. METHYLATION AT CPG SITES IN GENE PROMOTERS IS KNOWN TO AFFECT THE TRANSCRIPTION OF THE CORRESPONDING GENES. ABNORMAL REGIONAL HYPERMETHYLATION IS OBSERVED IN THE 5' REGION OF SEVERAL TUMOR SUPPRESSOR GENES (TSGS) IN HCC, AND THIS HYPERMETHYLATION MAY PROMOTE CARCINOGENESIS THROUGH THE TRANSCRIPTIONAL INACTIVATION OF DOWNSTREAM TSGS. THE DNA DAMAGE INDUCED BY OXIDATION IS A TRIGGER OF ABNORMAL DNA METHYLATION AND INACTIVATION OF TSGS THROUGH RECRUITMENT OF THE POLYCOMB REPRESSIVE COMPLEX TO THE PROMOTER SEQUENCE. THUS, OXIDATIVE STRESS MAY BE RESPONSIBLE FOR THE EMERGENCE OF HCC FROM CHRONIC HEPATITIS AND LIVER CIRRHOSIS THROUGH THE EPIGENETIC ALTERATION OF TSGS. THERE HAVE BEEN SEVERAL ATTEMPTS TO APPLY EPIGENETIC INFORMATION TO THE DIAGNOSIS AND TREATMENT OF HCC. THE PREDICTIVE VALUE OF SELECTED METHYLATION EVENTS ON SURVIVAL IN HCC PATIENTS HAS BEEN REPORTED, AND THE METHYLATION PROFILE OF BACKGROUND LIVER COULD BE ASSOCIATED WITH RECURRENCE-FREE SURVIVAL OF HCC PATIENTS WHO HAVE UNDERGONE HEPATECTOMY. ANOTHER STUDY DETECTED METHYLATED DNA FROM HCC CELLS IN SERUM, AND THE CIRCULATING TUMOR DNA WAS REGARDED AS A POTENTIAL TUMOR MARKER. IN ADDITION, SEVERAL TRIALS OF HCC THERAPY HAVE TARGETED THE EPIGENETIC MACHINERY AND WERE BASED UPON COMPREHENSIVE ANALYSES OF DNA METHYLATION OF THIS TYPE OF TUMOR. HERE, WE PRESENT AN OVERVIEW OF RESEARCH REGARDING DNA METHYLATION STATUS IN HUMAN HCC AND DESCRIBE THE CLINICAL APPLICATION OF EPIGENETIC INFORMATION TO HCC. 2014 15 4133 32 MECHANISMS OF HEPATITIS B VIRUS-INDUCED HEPATOCARCINOGENESIS. HEPATITIS B VIRUS (HBV) IS A MAJOR CAUSE OF HEPATOCELLULAR CARCINOMA (HCC). THERE ARE APPROXIMATELY 250 MILLION PEOPLE IN THE WORLD THAT ARE CHRONICALLY INFECTED BY THIS VIRUS, RESULTING IN NEARLY 1 MILLION DEATHS EVERY YEAR. MANY OF THESE PATIENTS DIE FROM SEVERE LIVER DISEASES, INCLUDING HCC. HBV MAY INDUCE HCC THROUGH THE INDUCTION OF CHRONIC LIVER INFLAMMATION, WHICH CAN CAUSE OXIDATIVE STRESS AND DNA DAMAGE. HOWEVER, MANY STUDIES ALSO INDICATED THAT HBV COULD INDUCE HCC VIA THE ALTERATION OF HEPATOCELLULAR PHYSIOLOGY THAT MAY INVOLVE GENETIC AND EPIGENETIC CHANGES OF THE HOST DNA, THE ALTERATION OF CELLULAR SIGNALING PATHWAYS, AND THE INHIBITION OF DNA REPAIR MECHANISMS. THIS ALTERATION OF CELLULAR PHYSIOLOGY CAN LEAD TO THE ACCUMULATION OF DNA DAMAGES AND THE PROMOTION OF CELL CYCLES AND PREDISPOSE HEPATOCYTES TO ONCOGENIC TRANSFORMATION. 2021 16 4462 44 MOLECULAR MECHANISMS OF HBV-ASSOCIATED HEPATOCARCINOGENESIS. HEPATITIS B VIRUS (HBV) CONTRIBUTES TO HEPATOCELLULAR CARCINOMA (HCC) DEVELOPMENT THROUGH DIRECT AND INDIRECT MECHANISMS. HBV-DNA INTEGRATION INTO THE HOST GENOME OCCURS AT EARLY STEPS OF CLONAL TUMOR EXPANSION AND INDUCES BOTH GENOMIC INSTABILITY AND DIRECT INSERTIONAL MUTAGENESIS OF DIVERSE CANCER-RELATED GENES. PROLONGED EXPRESSION OF THE VIRAL REGULATORY PROTEIN HBX AND THE LARGE ENVELOPE PROTEIN DEREGULATE THE CELLULAR TRANSCRIPTION PROGRAM AND PROLIFERATION CONTROL AND SENSITIZE LIVER CELLS TO CARCINOGENIC FACTORS. EPIGENETIC CHANGES TARGETING THE EXPRESSION OF TUMOR SUPPRESSOR GENES OCCUR EARLY IN THE DEVELOPMENT OF HCC. A MAJOR ROLE IS PLAYED BY HBX THAT IS RECRUITED ON CELLULAR CHROMATIN AND MODULATES CHROMATIN DYNAMICS AT SPECIFIC GENE LOCI. COMPARED WITH TUMORS ASSOCIATED WITH OTHER RISK FACTORS, HBV-RELATED TUMORS HAVE A HIGHER RATE OF CHROMOSOMAL ALTERATIONS AND P53 INACTIVATION BY MUTATIONS, OVEREXPRESS FETAL LIVER/HEPATIC PROGENITOR CELLS GENES, AND SHOW A SPECIFIC ACTIVATION OF THE AKT PATHWAY. THE WNT/BETA-CATENIN PATHWAY IS ALSO OFTEN ACTIVATED, BUT HBV-RELATED TUMORS DISPLAY A LOW RATE OF ACTIVATING BETA-CATENIN MUTATIONS. ALL AVAILABLE EVIDENCE STRONGLY SUPPORTS THE NOTION THAT CHRONIC HBV INFECTION TRIGGERS BOTH COMMON AND ETIOLOGY-SPECIFIC ONCOGENIC PATHWAYS, THUS PLAYING A DIRECT ROLE BEYOND STIMULATION OF HOST IMMUNE RESPONSES AND CHRONIC NECROINFLAMMATORY LIVER DISEASE. 2013 17 3932 34 LIVER REGENERATION, LIVER CANCERS AND CYCLINS. ACCUMULATING EVIDENCE HAS REVEALED THAT MALIGNANT CELL GROWTH IS REGULATED BY COMPLEX MECHANISMS INVOLVED IN GENETIC AND EPIGENETIC FACTORS. AMONG HUMAN CANCERS, CANCER IN THE LIVER (HEPATOCELLULAR CARCINOMA (HCC)) IS CHARACTERIZED BY THE EVIDENCE THAT IT IS USUALLY BASED ON CHRONIC LIVER DISEASES SUCH AS LIVER CIRRHOSIS OR CHRONIC HEPATITIS, IN WHICH THE LIVER IS PERSISTENTLY REGENERATING FOLLOWING HEPATIC INJURY. THIS RAISES THE POSSIBILITY THAT REPEATED HEPATOCYTE PROLIFERATION MAY CAUSE DISORDER OF GENES THAT ARE REGULATING THE CELL CYCLE IN HEPATOCYTES, THUS CAUSING HCC. IN THIS ARTICLE, RECENT STUDIES FOCUSING ON LIVER REGENERATION AND CANCER ARE REVIEWED FROM THE VIEWPOINT OF THE CELL CYCLE THAT IS REGULATED BY CYCLIN AND THE ASSOCIATED PROTEINS. 1998 18 2939 31 GENETIC AND EPIGENETIC ALTERATIONS IN HEPATITIS B VIRUS-ASSOCIATED HEPATOCELLULAR CARCINOMA. HEPATITIS B VIRUS (HBV) IS A MAJOR CAUSE OF HEPATOCELLULAR CARCINOMA (HCC). ITS CHRONIC INFECTION CAN LEAD TO CHRONIC LIVER INFLAMMATION AND THE ACCUMULATION OF GENETIC ALTERATIONS TO RESULT IN THE ONCOGENIC TRANSFORMATION OF HEPATOCYTES. HBV CAN ALSO SENSITIZE HEPATOCYTES TO ONCOGENIC TRANSFORMATION BY CAUSING GENETIC AND EPIGENETIC CHANGES OF THE HOST CHROMOSOMES. HBV DNA CAN INSERT INTO HOST CHROMOSOMES AND RECENT LARGE-SCALE WHOLE-GENOME SEQUENCING STUDIES REVEALED RECURRENT HBV DNA INTEGRATIONS SITES THAT MAY PLAY IMPORTANT ROLES IN THE INITIATION OF HEPATOCELLULAR CARCINOGENESIS. HBV CAN ALSO CAUSE EPIGENETIC CHANGES BY ALTERING THE METHYLATION STATUS OF CELLULAR DNA, THE POST-TRANSLATIONAL MODIFICATION OF HISTONES, AND THE EXPRESSION OF MICRORNAS. THESE CHANGES CAN ALSO LEAD TO THE EVENTUAL HEPATOCELLULAR TRANSFORMATION. THESE RECENT FINDINGS ON THE GENETIC AND EPIGENETIC ALTERATIONS OF THE HOST CHROMOSOMES INDUCED BY HBV OPENED A NEW AVENUE FOR THE DEVELOPMENT OF NOVEL DIAGNOSIS AND TREATMENTS FOR HBV-INDUCED HCC. 2015 19 2970 48 GENETIC AND EPIGENETIC SIGNATURES IN HUMAN HEPATOCELLULAR CARCINOMA: A SYSTEMATIC REVIEW. HEPATOCELLULAR CARCINOMA (HCC) IS THE THIRD MOST COMMON CAUSE OF CANCER DEATHS WORLDWIDE, AND THE INCIDENCE OF THIS FATAL DISEASE IS STILL ON RISE. THE MAJORITY OF HCCS EMERGE IN THE BACKGROUND OF A CHRONIC LIVER DISEASE, SUCH AS CHRONIC HEPATITIS AND LIVER CIRRHOSIS. THE CURRENT UNDERSTANDING IS THAT MAJORITY OF HCCS EVOLVE AS A CONSEQUENCE OF CHRONIC INFLAMMATION AND DUE TO THE PRESENCE OF INFECTION WITH HEPATITIS VIRUSES. THESE UNDERLYING PATHOGENIC STIMULI SUBSEQUENTLY INDUCE A SPECTRUM OF GENETIC AND EPIGENETIC ALTERATIONS IN SEVERAL CANCER-RELATED GENES, WHICH ARE INVOLVED IN CELL-CYCLE REGULATION, CELL GROWTH AND ADHESION. SUCH WIDESPREAD GENOMIC ALTERATIONS CAUSE DISRUPTION OF NORMAL CELLULAR SIGNALING AND FINALLY LEAD TO THE ACQUISITION OF A MALIGNANT PHENOTYPE IN HCC. IN GENERAL, THE TYPE OF GENE ALTERATIONS, SUCH AS POINT MUTATIONS, DELETION OF CHROMOSOMAL REGIONS AND ABNORMAL METHYLATION OF GENE PROMOTERS DIFFER ACCORDING TO THE INDIVIDUAL TARGETED GENE. IN HCC, INCIDENCE OF GENETIC ALTERATIONS IS RELATIVELY RARE AND IS LIMITED TO A SUBSET OF FEW CANCER-SPECIFIC GENES, SUCH AS THE TUMOR SUPPRESSOR P53, RB GENES AND ONCOGENES SUCH AS THE CTNNB1. IN CONTRAST, EPIGENETIC CHANGES THAT INVOLVE ABERRANT METHYLATION OF GENES AND OTHER POST-TRANSCRIPTIONAL HISTONE MODIFICATIONS OCCUR FAR MORE FREQUENTLY, AND SOME OF THESE EPIGENETIC ALTERATIONS ARE NOW BEING EXPLOITED FOR THE DEVELOPMENT OF MOLECULAR DIAGNOSTIC SIGNATURES FOR HCC. IN ADDITION, RECENT FINDINGS OF UNIQUE MICRORNA EXPRESSION PROFILES ALSO PROVIDE AN EVIDENCE FOR THE EXISTENCE OF NOVEL MECHANISMS FOR GENE EXPRESSION REGULATION IN HCC. IN THIS REVIEW ARTICLE, WE WILL REVIEW THE CURRENT STATE OF KNOWLEDGE ON THE ACTIVATION OF VARIOUS ONCOGENIC PATHWAYS AND THE INACTIVATION OF TUMOR SUPPRESSOR PATHWAYS IN HCC THAT RESULT IN THE DISRUPTION OF CANCER-RELATED GENE FUNCTION. IN ADDITION, WE WILL SPECIFICALLY EMPHASIZE THE CLINICAL IMPLICATION OF SOME OF THESE GENETIC AND EPIGENETIC ALTERATIONS IN THE MANAGEMENT OF HEPATOCARCINOGENESIS. 2011 20 5761 39 SOMATIC MUTATIONS, VIRAL INTEGRATION AND EPIGENETIC MODIFICATION IN THE EVOLUTION OF HEPATITIS B VIRUS-INDUCED HEPATOCELLULAR CARCINOMA. LIVER CANCER IN MEN IS THE SECOND LEADING CAUSE OF CANCER DEATH AND HEPATOCELLULAR CARCINOMA (HCC) ACCOUNTS FOR 70%-85% OF THE TOTAL LIVER CANCER WORLDWIDE. CHRONIC INFECTION WITH HEPATITIS B VIRUS (HBV) IS THE MAJOR CAUSE OF HCC. CHRONIC, INTERMITTENTLY ACTIVE INFLAMMATION PROVIDES "FERTILE FIELD" FOR "MUTATION, SELECTION, AND ADAPTATION" OF HBV AND THE INFECTED HEPATOCYTES, A LONG-TERM EVOLUTIONARY PROCESS DURING HBV-INDUCED CARCINOGENESIS. HBV MUTATIONS, WHICH ARE POSITIVELY SELECTED BY INSUFFICIENT IMMUNITY, CAN PROMOTE AND PREDICT THE OCCURRENCE OF HCC. RECENTLY, ADVANCED SEQUENCING TECHNOLOGIES INCLUDING WHOLE GENOME SEQUENCING, EXOME SEQUENCING, AND RNA SEQUENCING PROVIDE OPPORTUNITIES TO BETTER UNDER-STAND THE INSIGHT OF HOW SOMATIC MUTATIONS, STRUCTURE VARIATIONS, HBV INTEGRATIONS, AND EPIGENETIC MODIFICATIONS CONTRIBUTE TO HCC DEVELOPMENT. GENOMIC VARIATIONS OF HCC CAUSED BY VARIOUS ETIOLOGICAL FACTORS MAY BE DIFFERENT, BUT THE COMMON DRIVER MUTATIONS ARE IMPORTANT TO ELUCIDATE THE HCC EVOLUTIONARY PROCESS. GENOME-WIDE ANALYSES OF HBV INTEGRATIONS ARE HELPFUL IN CLARIFYING THE TARGETED GENES OF HBV IN CARCINOGENESIS AND DISEASE PROGRESSION. RNA SEQUENCING CAN IDENTIFY KEY MOLECULES WHOSE EXPRESSIONS ARE EPIGENETICALLY MODIFIED DURING HCC EVOLUTION. IN THIS REVIEW, WE SUMMARIZED THE CURRENT FINDINGS OF NEXT GENERATION SEQUENCINGS FOR HBV-HCC AND PROPOSED A THEORY FRAMEWORK OF CANCER EVOLUTION AND DEVELOPMENT BASED ON THE CURRENT KNOWLEDGE OF HBV-INDUCED HCC TO CHARACTERIZE AND INTERPRET EVOLUTIONARY MECHANISMS OF HCC AND POSSIBLE OTHER CANCERS. UNDERSTANDING THE KEY VIRAL AND GENOMIC VARIATIONS INVOLVED IN HCC EVOLUTION IS ESSENTIAL FOR GENERATING EFFECTIVE DIAGNOSTIC, PROGNOSTIC, AND PREDICTIVE BIOMARKERS AS WELL AS THERAPEUTIC TARGETS FOR THE INTERVENTIONS OF HBV-HCC. 2014